#include<bits/stdc++.h>
using namespace std;

int main(){
    long a,b,n;
    cin>>a>>b>>n;
    if(a==b&&b==n){
    	cout<<"0\n";
    	return 0;
	}
	long tem=n-b;
	long c=tem/(b-a);
	if(tem%(b-a)) c++;
	cout<<c*2+1<<"\n";
    return 0;
}
